Nasopharyngeal cancer (NPC) is a highly prevalent malignancy of middle-aged subjects in endemic regions such as the Pacific and Mediterranean Rim Countries and subarctic regions. NPC is a major cause of death from disease in Southern China. Genetic and environmental factors contribute to tumor risk, and the high incidence and high population densities in NPC endemic areas make NPC a common cancer globally. The estimated global population at high risk is 1.3-1.5 billion people. There are approximately 500 new cases in North America, 5000 cases in Hong Kong and Taiwan and 100,000 cases worldwide annually (Ung 1999). NPC is an unusual cancer because of its close, near absolute association with the human gamma Herpes Virus 4, Epstein-Barr Virus (EBV), with each tumor cell harboring copies of the same viral clone, detectable already in early, pre-invasive lesions (Pathmanathan 1995). NPC arises in the remote retronasal space, where it can develop with little symptomatology, and not rarely is it first diagnosed in metastatic tissue, with consequently poor prognosis (Skinner 1990; Ho 1998). Despite growing incidence and awareness in the relevant populations, the reality of NPC is still dominated by late diagnosis, usually through nasopharyngoscopy, with good prognosis for tumors detected at an early stage (Liu 1998).
For decades, the close association between EBV and NPC has attracted attempts to improve the clinical diagnosis of NPC risk. Raab-Traub (1987) demonstrated all histological subsets of NPC contain EBV DNA. While large surveys of EBV serology delineated significant associations (e.g. Zeng 1986), the ubiquitous EBV carrier status of nearly all humans prevented EBV serology from attaining clinical utility (Ho 1998). Serology is highly sensitive but lacks specificity.
The diagnostic promise of retronasal biopsies with detection of EBV genomes by molecular biology means was first demonstrated in 1992 (Feinmesser 1992). While the molecular detection of EBV genomes in biological samples has become a robust routine, the transition from small academic research studies (Tune 1999) to routine ambulatory application has been difficult because of a lack of dedicated, single use biopsy instrumentation and the need for rapid, local DNA isolation to avoid DNA degradation. Both present challenges, in particular in endemic regions with varied levels of technological infrastructure.